canon rumors FORUM

Be careful, the tolerance on the lens mount is tight beyond belief and they are aligned with expensive tooling and shims. Once they are disturbed, the camera will need to go to Canon to be re-aligned. Just a 1/10,000 inch will throw one side of a image out. Thats one of the reasons that a camera and lens should go in for a check when they are dropped.

Cine camera technicians align each lens with adjustments or shims because cinema is so demanding of perfection. Nikon farms out almost all production of lens parts, but keeps the lens mount rings in house because machineing is so critical. Canon does all theirs in house too.

At least I was smart enough to experiment on something first before messing with my $2000 camera:

I know I said it was my 5D2, but I actually was playing with the mount on my 25mm extension tube to make sure it could be removed easily enough first. The reason is that I have quite a scratched mount on my 5D2 and was thinking I could replace it if it were an easy job.

I simply said 5D2 in the thread to for simplicity for getting my question across.

Now that I know my answer, however, I have another question as a result of my stupid tinkering:

Since I had the four mount screws out on the extension tube, will that too throw the focusing out of whack when used with another lens?

Thanks for the help and everyone's patience. In the future I'll try to make myself leave this stuff alone and control my OCD better.

At least I was smart enough to experiment on something first before messing with my $2000 camera:

I know I said it was my 5D2, but I actually was playing with the mount on my 25mm extension tube to make sure it could be removed easily enough first. The reason is that I have quite a scratched mount on my 5D2 and was thinking I could replace it if it were an easy job.

I simply said 5D2 in the thread to for simplicity for getting my question across.

Now that I know my answer, however, I have another question as a result of my stupid tinkering:

Since I had the four mount screws out on the extension tube, will that too throw the focusing out of whack when used with another lens?

Thanks for the help and everyone's patience. In the future I'll try to make myself leave this stuff alone and control my OCD better.

Extension tubes are very precisely machined as well, the good ones, anyway. Most tube users are not worried about edge to edge sharpness, and you are magnifying the image anyway to only see the center portion.

Unless you see a problem with the image, don't worry. I would avoid messing with the camera mount though.

canon rumors FORUM

Don't listen to these guys - take a chainsaw to that puppy and field strip it!

Seriously though, if yer REALLY worried about the scratched mount, here's food for thought. Is it just an appearance thing, like surface scratches? Or is it gouged, as in you had grains of sand on there when you mounted a lens. I suspect it's just appearance. You could try polishing, but only if it's something that will keep you awake at night. Practice on the extension tube with a cotton swab (Q-tip) and a small dab of metal polish like Brasso. Be careful, even if it works, when you do it to the camera you might use too much and it might drip into the camera body. Plus the whole time you're doing this, dust is falling into the camera body. My point is, cosmetic mount scratches are nothing to worry about. Put that OCD on the shelf and take some photos. And put your extension tube back together, it's fine.

At least I was smart enough to experiment on something first before messing with my $2000 camera:

I know I said it was my 5D2, but I actually was playing with the mount on my 25mm extension tube to make sure it could be removed easily enough first. The reason is that I have quite a scratched mount on my 5D2 and was thinking I could replace it if it were an easy job.

I simply said 5D2 in the thread to for simplicity for getting my question across.

Now that I know my answer, however, I have another question as a result of my stupid tinkering:

Since I had the four mount screws out on the extension tube, will that too throw the focusing out of whack when used with another lens?

Thanks for the help and everyone's patience. In the future I'll try to make myself leave this stuff alone and control my OCD better.

Extension tubes are very precisely machined as well, the good ones, anyway. Most tube users are not worried about edge to edge sharpness, and you are magnifying the image anyway to only see the center portion.

Unless you see a problem with the image, don't worry. I would avoid messing with the camera mount though.

Thanks again for your response. I always look for your's and Neuro's posts for good information. In this case you saved me from doing something particularly stupid. Much appreciated.

I played with the extension tube a bit with the 100mm L Macro and everything seemed to be fine. Like you said, edge sharpness is not really a priority with extension tubes, anyways.

Don't listen to these guys - take a chainsaw to that puppy and field strip it!

Seriously though, if yer REALLY worried about the scratched mount, here's food for thought. Is it just an appearance thing, like surface scratches? Or is it gouged, as in you had grains of sand on there when you mounted a lens. I suspect it's just appearance. You could try polishing, but only if it's something that will keep you awake at night. Practice on the extension tube with a cotton swab (Q-tip) and a small dab of metal polish like Brasso. Be careful, even if it works, when you do it to the camera you might use too much and it might drip into the camera body. Plus the whole time you're doing this, dust is falling into the camera body. My point is, cosmetic mount scratches are nothing to worry about. Put that OCD on the shelf and take some photos. And put your extension tube back together, it's fine.

All very good advice, thank you. I appreciate your suggestion about using metal polish, but I think I'll take your latter advice and just take some photos and try to put this behind me; it's safer and more fun anyways!

At least I was smart enough to experiment on something first before messing with my $2000 camera:

I know I said it was my 5D2, but I actually was playing with the mount on my 25mm extension tube to make sure it could be removed easily enough first. The reason is that I have quite a scratched mount on my 5D2 and was thinking I could replace it if it were an easy job.

I simply said 5D2 in the thread to for simplicity for getting my question across.

Now that I know my answer, however, I have another question as a result of my stupid tinkering:

Since I had the four mount screws out on the extension tube, will that too throw the focusing out of whack when used with another lens?

Thanks for the help and everyone's patience. In the future I'll try to make myself leave this stuff alone and control my OCD better.

Extension tubes are very precisely machined as well, the good ones, anyway. Most tube users are not worried about edge to edge sharpness, and you are magnifying the image anyway to only see the center portion.

Unless you see a problem with the image, don't worry. I would avoid messing with the camera mount though.

So would you say over time all lens mounts need adjusting just from long-term use? I would assume that putting heavier lenses on the camera would also theoretically loosen the lens mount as the metal and plastic fatigues over time.